Editing Phosphorus (section)

===Atomic properties===
A phosphorus atom has 15 electrons, 5 of which are [[valence electron]]s. This results in the [[electron configuration]] 1s<sup>2</sup>2s<sup>2</sup>2p<sup>6</sup>3s<sup>2</sup>3p<sup>3</sup>, often simplified as [Ne]3s<sup>2</sup>3p<sup>3</sup>, omitting the [[core electron]]s which have a configuration equivalent to the [[noble gas]] of the preceding [[period (periodic table)|period]], in this case [[neon]]. The molar [[ionisation energies]] of these five electrons are 1011.8, 1907, 2914.1, 4963.6 and 6273.9&nbsp;k[[joule per mole|J⋅mol<sup>−1</sup>]].

Phosphorus is a member of the [[pnictogen]]s (also called [[group (periodic table)|group]] 15) and [[period 3 element]]s, and many of its chemical properties can be inferred from its position on the [[periodic table]] as a result of [[periodic trends]]. Like [[nitrogen]], [[arsenic]] and [[antimony]], its main [[oxidation state]]s are −3, +3 and +5, with every one in-between less common but known. Phosphorus shows as expected more [[electronegativity]] than [[silicon]] and arsenic, less than [[sulfur]] and nitrogen, but also notably less than [[carbon]], affecting the nature and properties of P–C bonds. It is the element with the lowest [[atomic number]] to exhibit [[hypervalence]], meaning that it can form more [[chemical bond|bond]]s per atom that would normally be permitted by the [[octet rule]].